Biodiversity and pizza – an extended analogy leading to a call for a more multidimensional treatment of nature

I’ve been thinking a lot lately about the term biodiversity. Not so much its scientific defintion as its usage in public discussions. No doubt this is because I am increasingly using the word biodiversity to describe my own work as I move in more applied directions. And a few weeks ago I got to spend over an hour with a reporter talking about the history and implications of using the term biodiversity. She asked good questions and forced me to get clear about what I really think. So I’ve got a lot of thoughts rattling around in my brain on the usefulness of term “biodiversity” that I would like to discuss with the community.

Biodiversity is a really important term that is being woven into the international regulatory framework at the moment. But biodiversity is also an emotion laden term in ecology these days. So … I’m going to adopt the philosopher’s trick and talk about something completely different for a bit (pizza!) and then circle back and tell you I was really talking about biodiversity all along.

Biodiversity=Pizza?

Imagine we have some good, some thing, in mind that we passionately believe is excellent and the world needs more of it and and that the world generally needs to get busy paying attention to it. This could be books, it could be food in general. For many it could be coffee or wine (or for ecologists beer). For me it is going to be pizza.

So the first thing I want to look at is what do I mean when I say we need “more” pizza. I would argue there are at least three different senses of “more” that could be relevant:

1. Absolute quantity – I probably literally want more pizzas in the world. This could be measured directly by counting the number of pizza pies or the total kilograms of pizza produced per day. It might also mean pizza availability in every corner of the world, measured by say 100 km x 100 km pixels in which pizza is sold.
2. Diversity of types – one of the reasons I love pizza is how diverse it is. There’s New York/Boston pizza with a thin crust and cheese so thick you need a chisel (and lots of napkins to soak up the grease), there’s west coast pizza with an inch of toppings, there’s Chicago deep-dish pizza, there’s true Italian pizza with sparing doses of everything but scrumptious ingredients and a crunchy crust. There’s Hawaiian (my favorite), there’s pepperoni. You can even start playing with the sauce and do barbeque Thai chicken, or pesto and four cheeses. I love the diversity of pizza! We could quantify this by counting the total number of toppings offered on menus or doing a Shannon-Weiner index on pizza styles (e.g. p_Chicago=0.10).
3. Quality – If I want the “pizza-ness” of the world to increase I probably want overall pizza quality to increase too. I’m not going to be happy if my efforts mostly result in frozen cardboard pizzas taking over the world. This one is tricky because while there are probably some universally agreed upon dimensions to quality (fresh>frozen), there are also a lot of personal preferences. I love Hawaiian but I have at least two friends who tell me that putting pineapple on a pizza is evil (their words, not mine). And there are people who won’t touch deep dish pizza and people who will only eat deep dish. We can’t really quantify this one. Its too subjective. All we can do is quantify what is available now and and what used to be available.

The second thing I want to look at is now imagine I have taken my pizza love into genuine activism and have started lobbying the world for more pizza. I’ll probably mostly talk to governments and corporations. It won’t be long until I hit a politician or a company boss who looks me in the eye and tells me that I’m crazy, hamburgers are a much more basic and popular food than pizza. Now I have a big choice to make. Do I stick with my basic inherent belief that pizza is good and that much of the world loves pizza (even if some hate it). That between the passionate supporters of pizza and the silent majority that have positive if weak feelings, I can carry the day for more pizza. Or should I start talking about how useful pizza is because it has all four food groups in one food (at least before the US government redefined the food groups), that the anti-oxidants in tomato sauce are very healthy, that pizza is very practical since it can go from the school cafeteria to gourmet restaurants and does OK (compared to other foods) at being kept warm for a while. And etc. In short do I move beyond pizza is good into pizza is practical? or stick with pizza is good and start showing mouth-watering pictures of a steaming, chewy slice of pizza?

The three important questions

Since I tipped my hand so strongly at the beginning, you have probably already figured out that I could repeat the whole discussion replacing the word “pizza” with the word “nature” or even “biodiversity”. Now I want to leverage the analogy to pose three main questions.

1. Of the 3 aspects of “more” (total quantity, diversity, quality or type) which ones should we emphasize in the public sphere? Indeed which ones are most important?
2. Is the word “biodiversity” more analogous to “pizza” or “pizza diversity of types”? In other words is biodiversity a generic concept that captures our warm fuzzy feeling about nature (and ultimately all 3 aspects of “more”)? Or is it a much more specific term that is truly only about diversity of pizza types/species (and genes etc) and ignoring quantity and quality?
3. Was I better off when I ran into opposition switching to a utilitarian argument (“pizza is healthy”, “biodiversity provides ecosystem services”) or sticking to my guns and knowing I had a good brand that polled well and just selling my concept (be it pizza or biodiversity)?

These three questions are, I believe, fundamental questions facing people advocating for biodiversity right now. And there is a lot of disagreement on the answers. I will give my own personal answers in a minute. But let me also emphasize that most of what I am about to say is necessarily opinion and intelligent people will disagree (sometimes strongly). Short of changing the course of entire public discussions in a controlled experimental fashion there is no way to objectively determine who is right and wrong. So I could easily be wrong. But the current approach to public discussion could also easily be wrong. My main goal of this post is not to win the day for my opinions,  but just to at least clearly pose the right questions and start a conversation about them.

Go ahead and take a minute to actually think about and answer these 3 questions for yourself. I’m arguing they’re fundamental. You really should have an opinion …

I’ll wait …

My answers to the 3 questions

My own answers are:

1.  Which aspect?: all of them of course. There is no reason to pick only one. They are all key components. Per question #2, I’m not quite sure whether the word biodiversity was intended to specialize on just the diversity aspect or not, but it has had that effect and it is unfortunate. If we only cared about biodiversity sensu strictu, at its logical extreme we could just build a super-zoo and be done with it. The degree to which that would be unsatisfying shows pretty clearly that we care about the other aspects (i,e. quantity and quality) as well..
2. Biodiversity as a generic good or specifically diversity?: I honestly don’t know. It has been a strength and a weakness of the term that it has both connotations. I am really on the fence on what should be used going forward. Biodiversity is really strongly tied to the narrower concept of diversity these days, and it is hard to miss that this is in the name. But biodiversity has a lot of momentum including the UN Convention on Biodiversity and the ensuing IPBES (Intergovernmental Panel on Biodiversity and Ecosystem Services). But terms like nature and wildlands worked well in the 1970s. Ultimately I am going to waffle on this one.
3. Keep ecosystem services or sell nature for nature’s sake?: Again, why choose? Both utilitarian and aesthetic/spiritual arguments make a lot of sense. Although I do think the pendulum has swung way too far to the utilitarian/ecosystem services side, and thus I would advocate for an increase again in advocating nature for its own sake. But ultimately the answer has to be “all of the above.”

So in short, I am arguing the public discussion about how humans are impacting nature, about what aspects of nature needs to be preserved and why nature needs to be preserved, needs to be an all included approach (quantity, diversity, quality, utility, for its own sake), not to pick a more limited approach (e.g. diversity and utility only or primarily). My opinion is hardly original or isolated (e.g. papers by McCauley, or history of ideas by Mace), but it is a bit out of step with my sense of the current prevailing paradigm which seems to me to primarily justify conservation by invoking only ecosystem services and biodiversity sensu strictu (i.e. just diversity of species) (e.g. paper by Cardinale). It is worth noting that all 3 of those papers were published in Nature so I’m hardly claiming my view is censored. But the Cardinale paper attracted 1083 citations and the McCauley paper only 447 despite the McCauley paper having been around 3 times as long (or in other words McCauley is cited about 50 times/year, Cardinale et al 300 times/year). But this prevailing view of diversity and ecosystem services leaves three  dimensions of nature (quantity, quality, and innate value of nature off the table). And I think that is regrettable.

I respect that there are diverse opinions. I don’t think the other scientists are wrong. And questions centered on biodiversity and ecosystem are very interesting scientific questions (I put a lot of energy into the first one myself). And I don’t think anyone’s motives are at question here. But questions of how best to assess human impact on nature and to advocate for nature are too important to sweep under the rug. Or to have an orthodoxy. Or to shut down conversation for fear the public is watching.

My two-pronged logic for my answers to the 3 questions

My reasoning for my answers to the three questions is two-fold.

First, I have a practical problem. The science doesn’t support only focusing on diversity and ecosystem services. Consider the salt marsh. It is one of the most productive ecosystems around. It has a spare beauty that appeals to many people. And it provides an important ecosystem service of regulating flood tides for the human developments on the other side of the marshes from the open ocean. And it is one of the most threatened ecosystems of all (at least in the temperate world). So we should be pouring conservation dollars into it right? Well, actually if our only justifications for nature are ecosystem services and diversity, then no. Salt marshes are startlingly species poor (indeed it is an interesting basic science question – how can such a productive environment have so few species). If we paved over all the large salt marshes of the eastern US we would lose a few (probably less than half a dozen) species of bird, and maybe an invertebrate or two. And maybe a few more stragglers. Not zero loss, and certainly tragic. But if we’re trying to conserve biodiversity sensu strictu, it would have to rate pretty low on the prioritization list. And as far as ecosystem services, lets just plant invasive Phragmites that grows into a dominant monoculture 3x as high as the native cordgrasses and therefore much more effective at flood control and at least as good at other ecosystem services (e.g. nursery to ocean species). In short, if we can’t invoke quality of ecosystem (e.g. which species are living there) and the innate value of salt marshes (that spare beauty I mentioned), maybe we should just be actively planting Phragmites. Ecosystem services and biodiversity are poor justifications for protecting the salt marshes, something that I (and everybody else with an environmental bone in their body) believes is important. This is arguing by anecdote, but the anecdotes are numerous (we could have a good conversation about buffel grass, nile perch, and etc). Limiting our quiver to only two arrows is a bad idea.

Less anecdotally, what do meta-analyses tell us about hanging our hat solely on biodiversity and ecosystem services?  I am now leaving hot water to boiling oil. But I’m going to present my views anyway. This blog is ultimately about conversation. I hope we have a CVIL & FACT-BASED conversation in the comments. In short, there is growing evidence that the main impacts humans are having on nature are on #1 (quantity) and #3 (quality or which species) and not so much on #2 (biodiversity sensu strictu). Specifically, humans are greatly impacting #1 (total quantity- we have modified about 50% of the terrestrial earth for human uses and harvested many organisms such as marine fish to drastically reduced numbers). We are also drastically impacting #3 (i.e. we have changed the composition of communities creating winners and losers – one study found 10% of the species turns over every decade in the average community, Dornelas et al. 2014 (also see Supp & Ernest 2014). But many local communities have changed very little in #2 (true biodiversity=variation) (e.g. Vellend et al 2013; Dornelas et al 2014; Supp & Ernest 2014; Newbold et al 2015*; Elahi et al 2015 but see Murphy & Romanuk 2014**). And even the fear of a “biodiversity crisis” or impending 6th mass extinction is more a projection about what could happen than something that has already happened (documented extinctions since 1500 in the two best known groups are 129 extinctions out of ~10,000 species for birds and 61 out of ~5,500 for mammals or around 1% in 500 years with only 6/9,900 and 3/5,400 or around 0.05% in 500 years if you exclude evolutionarily isolated islands***  which you should probably do if you’re going to extrapolate – see Briggs).

To be clear, am I saying humans aren’t having a negative impact on nature? No. I definitely believe humans are drastically changing the face of nature to something unrecognizable. And I am very disturbed by that. I just think that the picture using only diversity and ecosystem services is much more mixed than if we look at all five dimensions. Which is why I think we should focus on all five dimensions.

 

Figure 1 – Google N-gram relative usage of different words capturing nature’s value. Generic terms like “nature” and “environment” come out much higher than technical terms like “biodiversity” or “ecosystem function”.

My secondary argument is also a practical one. Advertisers have known for a long time that when you want to influence people, emotions work better than rational arguments. Advertisers focus on fear plus peer (and sexual partner) acceptance. Politicians primarily use a mix of fear and hope. Research clearly shows scare tactics such as the gruesome pictures on cigarette packages in much of the world work much better than telling you the odds of getting cancer or a shortened lifespan. Physicists and astronomers have sold billion dollar projects such as the Large Hadron Collider and the Hubbell telescope primarily by focusing on emotional sells like the frontier, the unknown, the grandeur. They well know that if they tried to get into a dollar and cents justification, they would lose. Or see what words connect with the general public using Google Ngram (Figures 1 and 2), albeit certainly with a grain of salt. Generic emotional terms like “nature”, “environment” and “ecology” are used most often. Meanwhile, “wilderness” – a quality oriented term is trending up while “biodiversity” (a diversity oriented term) actually peaked in 2002 and is trending down. “Ecosystem services” barely even registers outside the scientific and policy communities. The environmental movement was launched on books like Rachel Carson’s Silent Spring (an emotion-laden quantity and quality argument). And I vividly remember the publicservice ad campaigns in the 1970s focused on emotional impact including a picture of people throwing trash out of a car creating an ugliness followed by a Native American with a tear rolling down his cheek (another emotion laden quality argument). So this is a second reason I think we should get back to selling nature for nature’s sake and not just for ecosystem services. Biodiversity is more in the middle – it touches some emotional buttons (which is part of why it was picked), but it doesn’t touch as many buttons as “nature”, “wilderness”, “environment” or “keep the woods I vacationed in as a kid looking like the woods I vacationed in as a kid”.

Figure 2- From Google N-gram (nature and environment removed to show tends in lower ranked words)

 

Can scientists handle talking about quality of nature?

Why aren’t scientists already invoking all five dimensions instead of just ecosystem services and biodiversity? I think it is pretty simple. Scientists are comfortable with things that are clear cut and quantitative. Biodiversity sensu strictu and ecosystem services fit this paradigm (x species, y$ of ecosystem services). We’re also pretty good at talking about quantity (x% of forest converted to second growth, y% of large fish in the sea removed). But nature for nature’s sake and quality (which species should be there) are much more subjective. They are normative (human values), not innately quantitative. This makes us uncomfortable. And it means we don’t have the best/only opinion around. Other people’s opinions are equally valid to those of scientists about whether phragmites or a native salt marsh is more desirable. This loss of quantiative objective tools and having to share the stage with other opinions is uncomfortable for scientists.

But we have to be willing to move into these areas (or alternatively stop saying biodiversity and ecosystem services are the only worthwhile metrics and then let people more comfortable in public policy advocacy on normative issues move into the full five dimensional discussion). Because these quality/quantiaty/nature-for-its-own-sake are often times the biggest kinds of impacts we’re having on nature. There are plenty of examples of an invasive plants that increases biomass and increase ecosystem services and not infrequently even increase diversity. Creating edges (e.g. by roads or forest fragments) can often increase diversity.  The inconvenient truth is that if we only care about how many species are there in our favorite plot of land and are OK with the changes to which species show up, then an awful lot of plots of land are doing just fine thank you. We scientists have to start finding a way to be comfortable talking about what biodiversity we want, not just how much and how many.

Like I said, part of the answer may be to let people who are more comfortable with normative discussions take over part of the conversation. But I do think scientists have a role even when talking about quality and nature for nature’s sake. Simply documenting what changes are happening and how quickly they are changing is an important piece of data in this conversation and that is the kind of simple objective, quantitative conversation scientists are comfortable with. And the answer of how much humans have changed nature in this aspect of quality (who is there) is, in simple technical objective terms, ginormous. And I do believe lots of people care about that.

Conclusion

So to summarize, what has pizza taught us about biodiversity? What do we need to do to better advocate for the pizza (err ecosystems) we love? 

1. As a scientist, and trying to preserve scientific credibility well into the future, I am very uncomfortable with the logical inconsistencies that only promoting biodiversity and ecosystem function puts me into – namely that often times invaded, heavily changed ecosystems are “better” by those measures and similarly by those measures humans aren’t having much impact on many parts of the planet.
2. Therefore, we need to expand out from just biodiversity sensu strictu and ecosystem services to a fully multidimensional view of nature that includes quantity, quality and nature for nature’s sake.
3. To do this, scientists will have to find a way where we’re comfortable in starting and participating in “quality” discussions (which species should be there). How best to do this may vary from scientist to scientist.

What do you think? How can we most effectively advocate for biodiversity? Is biodiversity a useful term or has it outlived its usefulness? Should we be selling ecosystem services too? How about quality, quantity and nature for nature’s sake? Have I at least asked the right questions? As regular readers know, I highly value dialogue, and am in sincere in wanting to have a conversation, including viewpoints different than my own. But the conversation needs to be factual (e.g. citations or examples) and not or argument by bluster and especially not ad hominem  .

---

* I am aware the authors present their paper as a sign of a major crises, but the fact is it shows that the decline in richness sensu strictu (after controlling for changes in quantity) is about 8% total over 500 years even when you include every parking lot and cornfield in the globe (and as I’ve noted elsewhere still has one serious bias of using large rainforest->cornfield losses in estimating the more common but smaller prairie->cornfield losses), it is hard for me to read this paper as a sign of drastic biodiversity loss
** We could have a long conversation about why this one paper seems to be contrary to the trends everybody else is finding – in my opinion short story is that they set out to measure something different
*** Australia was classified as an island in this analysis – you can debate this, but the overall picture only changes in degree